Route reliability record

ROC→ORD

Rochester to Chicago

Flights: 2,340
Period: July 2025 to June 2026
Distance: 528 mi
Carriers: 4

This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 2,340 flights, of which Republic Airways flew 711 at 81.1% on time.

Republic Airways is the most reliable of the three carriers covered here at 81.1% on time across 711 flights.

On time

74.7%

Arrivals under 15 minutes late, of 2,288 completed flights

Avg delay

92 min

Across delayed arrivals only, not all flights

Cancelled

2.14%

National rate is 1.81%

Best carrier

Republic

81.1% on time across 711 flights

These figures cover 2,340 flights between July 2025 and June 2026. Beyond the headline rate, 10.9% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Which airline is most reliable on ROC to ORD

The choice of carrier is not cosmetic here. Republic Airways arrives on time 81.1% of the time; United Airlines manages 67.6%. Sample sizes sit next to every figure, because a two-point gap across 591 flights means less than a ten-point one.

On-time performance by carrier on ROC to ORD
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airways	711	81.1%	86 min	2.39%	B
Envoy Air	813	77.8%	87 min	2.21%	B
United Airlines	591	67.6%	85 min	1.35%	C
SkyWest Airlinesthin sample	225	62.4%	133 min	3.11%	D−

The spread between Republic and United is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 37 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am704 flights84.9%
8am–11am162 flights90.1%
11am–2pm675 flights81.8%
2pm–5pm96 flights75.5%
5pm–8pm616 flights52.9%
8pm–5am87 flights58.8%

Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 52.9% on time, against 90.1% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 704 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 19 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.May best, December worst

December is the weak month at 63.3% on time, against 82.2% in May. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. November was the busiest month here, with 225 flights.

Across the week, Tuesday is the strongest day at 78.3% on time and Sunday the weakest at 68.6%. 10 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 53,000 reported delay minutes.

Late-arriving aircraft
36%
National Airspace System
36%
Carrier
25%
Extreme weather
3%
Security
0%

36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 53,000 reported delay minutes here, that single category outweighs weather by 12 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 53,323 reported delay minutes.

36% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 19,000 minutes out of 53,000, against a national NAS share of 21%.

Cancellations sit at 2.14% against a national 1.81%, which is ordinary. Diversions add another 0.09%.

Connections and stage length

What a delay here actually costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.9% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 528 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 74.2% on time across 2,320 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 2,340 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 82.2% on time and December 63.3%, a swing of 19 points. If the dates move at all, move them out of December before you think about anything else. 2,288 completed flights over 12 months sit behind that.

Common questions

ROC to ORD questions

How often is ROC to ORD delayed?

About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.3% of the 2,340 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.

Which airline is most reliable on ROC to ORD?

Republic Airways leads at 81.1% on time across 711 flights. United Airlines is at the other end on 67.6%, a gap of 14 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on ROC to ORD?

The 8am–11am departure window is the strongest at 90.1% on time. The 5pm–8pm window is the weakest at 52.9%, 37 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are December delays on ROC to ORD?

December is the weakest month at 63.3% on time, compared with 82.2% in May. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. ROC to ORD and ORD to ROC are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures